exhaust vs wear down

exhaust is a noun but wear down is not a noun.

Word	Noun	Adjective	Verb	Adverb
exhaust	Yes	No	Yes	No
wear down	No	No	Yes	No

As verbs, wear down is a hypernym of exhaust; that is, wear down is a word with a broader meaning than exhaust:

Other hypernyms of exhaust include fag, fag out, fatigue, jade, outwear, tire, tire out, wear, wear out, wear upon, weary.

exhaust (noun)	wear down (noun)
system consisting of the parts of an engine through which burned gases or steam are discharged
gases ejected from an engine as waste products

exhaust (verb)	wear down (verb)
wear out completely	exhaust or get tired through overuse or great strain or stress
eliminate (a substance)	deteriorate through use or stress
use up the whole supply of
use up (resources or materials)
deplete